Europe eyes six Martian landing sites

The European Space Agency (ESA) has compiled a shortlist of places it would like to look for life (past or present) on Mars.

Artist's impression of the Rover. Credit: ESA

The agency says its ExoMars mission, planned for a 2013 launch, will touch down on some of the red planet's oldest rocks, as these might once have been in contact with Martian water. A region rich in clay minerals would be ideal, the agency said, since these so-called phyllosilicates contain water in their crystalline structure.

Planetary researcher Dr Jean-Pierre Bibring, from the University of Paris, told the BBC: "Phyllosilicates are not just regions where we think water must have been. We also think they are places that helped reactions to take place. On the early Earth, all the primordial biochemistry took place in phyllosilicates as well."

The ExoMars mission will follow a similar mission from the US. ESA says NASA is considering similar potential landing sites, but that there is no chance both agencies will go for the same option.

The mission is expected to cost of the order of a billion Euros, with half of that money going on the industrial costs of designing and constructing the craft. Initial designs have been approved, but the finer details, such as what kind of rocket it will launch on, are still up for discussion.

Whatever form the mission takes, and wherever it lands, it must be a rover capable of roaming over the surface of Mars, drilling two metres into the surface and analysing the soil samples it collects.

The pre-launch process will also be complicated, because the craft must be totally sterile before it heads into space, to avoid contaminating the landing site with life from Earth. Spending €1bn to rediscover the common cold would not make for a happy space agency, after all.

The shortlist

The shortlist includes a valley, two craters, two possible sites on one plain, and the surface of an impact fracture. Mawrth Vallis is filled with light coloured clay minerals, while similarly clay-rich debris covers the surface of the Nili Fossae fracture. Holden Crater is thought to be an ancient lake bed, while Gale Crater is left from an impact, but has exposed layered deposits. The final two sites are both on the Meridiani Planum. ®